Following a dark and stormy night, the weather had cleared by morning and Corvette Team Leader Tommy Morrison was at the helm of the Corvette ZR-1 when it happened. Exactly twenty-four hours after the start, at precisely 9:55:12 a.m. on March 2, 1990, Corvette became a World Class sports car when the ZR-1 broke a 24-hour land speed record that stood for fifty years. The Corvette averaged an astonishing 175.885 mph for twenty-four hours, annihilating the old record of 160.180 mph. It was such a prodigious accomplishment that no one could possibly deny Corvette’s status as a World Class sports car.
ZR-1 King of the Hill
The American Heritage Dictionary defines World Class as: “Being among the best or foremost in the world; of an international standard of excellence.” For the past several generations, Corvette has been considered to be a World Class sports car and with the recent introduction of the mid-engine C8 Corvette it will remain so for the foreseeable future. But America’s sports car did not always enjoy such celebrated status. Before the C4, big block Corvettes had plenty of acceleration but lacked superior handling that a sophisticated chassis could provide. Beginning in 1984, the C4 chassis gave Corvette the handling to compete against the best in the world, but their engines became strangled by increasingly stringent exhaust emissions standards. The Corvettes at the time lacked World Class speed performance.
As the 1980s faded into the 1990s, it became apparent to Corvette Chief Engineer Dave McLellan that the Vette needed a serious boost in power to challenge the best in the world. The Corvette engineering team pursued a variety of ways to increase the power while still being able to meet all of the exhaust emission requirements. One of the ideas they considered was new double overhead cam (DOHC) cylinder heads for the standard Corvette small block engine. After consulting with their engineering partners Group Lotus, then owned by General Motors, it was discovered that such an engine would not fit between the chassis frame rails and, therefore, could not be assembled from below the chassis, a necessity for production at the Bowling Green assembly plant.
The only practical solution to accommodate the production requirements for the DOHC engine was to give the new engine its own block, which also meant a significant increase in the ZR-1 development costs. GM looked to Group Lotus to design and develop the engine, and brought in Mercury Marine, a small marine motor manufacturer with an exceptional quality record, to produce the new engine known as the LT-5. The powerplant for the “King of the Hill”, as the ZR-1 became known, displaced 350 cu. in. utilized an aluminum block, double overhead cam cylinder heads with four valves per cylinder, and multi-port fuel injection to produce 375 horsepower initially, which was boosted to 405 horsepower from 1993 on. Not earth-shaking by today’s horsepower standards, but it was a force to be reckoned with at the time.
The Corvette ZR-1 now had the chassis and the engine to become a World Class sports car, but just talking about your fancy new engine in a great-handling chassis doesn’t cut it. You can’t just claim to be World Class—you have to do something spectacular to earn the reputation. And that’s just what the Corvette Team did!
Hatching a Plan to Break the 50-Year Land Speed Record
The existing world record for average speed for twenty-four hours in 1990 was 160.180 mph set by Ab Jenkins and Cliff Bergere in July of 1940 driving the Mormon Meteor III, a purpose-built land speed record car nearly twenty-one feet long, weighing 4,800 pounds and powered by a 25.7 liter (1,570 cu. in.) Curtiss Conqueror airplane engine. At the time, this was the only significant pre-World War II land speed record still standing.
A team of Corvette engineers and racing drivers were audacious enough to think that that they could break the Mormon Meteor III’s record with a production ZR-1. After discussions among John Heinricy, Corvette/Camaro Product Engineering Manager and racing driver extraordinaire, racing driver/car owner Tommy Morrison, driver Stu Hayner, and Jim Minneker, Corvette Powertrain Manager, the group was convinced. Said Minneker, “This old record for 24 hours was 161 mph and we had a production car in street trim that had a top speed of 180 mph. It looked like a no-brainer.” Tommy Morrison was even more excited by the possibility. He told the group, “We’ve got to do this!”
GM and Chevrolet say “No, thanks”
Heinricy discussed the plan with Corvette Chief Engineer Dave McLellan who was enthusiastic about the idea. But, as word of the project spread upward through Chevrolet and GM management, the team ran into a corporate brick wall. Herb Fischel, head of GM motorsports and Ralph Kramer, Director of Chevrolet PR and Communications, were adamantly opposed to the whole idea. Both men thought there was too much opportunity for something to go wrong and that the overall chance of success was so small that it did not justify GM or Chevrolet corporate involvement.
While upper management refused to lend any support, financial or otherwise, to the project, it didn’t flat out say to the GM employees involved, “You can’t do this.” The team was to go underground and do all of their preparation work in strict secrecy. The car they used was one of Jim Minneker’s 24-hour track testing cars because they knew it could last and it was already equipped with a roll cage and fire extinguisher system. All of the GM employees involved in the project had to use vacation leave for any time away from their offices to prepare, test, and run the car in its record attempt. There was no official encouragement from either General Motors or Chevrolet.
Corvette Team Persists in Planning and Testing
The Team immediately began the hunt for sponsors and initiated detailed planning for the record attempt. Morrison provided the resources of his Morrison Engineering and Development race shop and convinced his racing sponsor, Mobil Oil, to sign on as a major sponsor. Driver Stu Hayner brought his backers, GM’s EDS Division, the Southern California Chevrolet Dealers Association, and Goodyear on board as major sponsors.
Heinricy, Hayner, Morrison, and Minneker committed themselves to drive the car. Realizing that additional driving help was needed to safely drive the car at speeds of 180-plus mph for 24 hours, driver Don Knowles, Corvette development engineer Scott Allman, and experienced Showroom Stock drivers Scott Lagasse and Kim Baker were recruited for the effort. If all went according to plan, the drivers would hit speeds in the low 190s along the straights and would be running at 175-180 mph through the turns. Those speeds were calculated to break the record allowing for a pit stop every 80 to 90 minutes for fuel and to change tires and drivers.
Deep in the Heart of Texas
According to Anthony Young in his ZR-1 book Heart of the Beast, “The track chosen would have a direct bearing on the car’s ability to last and the strain put on the drivers. For that reason, the high-banked tracks of Daytona and Talladega were eliminated.” The site selected was a 7.7 mile unbanked paved oval at the Bridgestone/Firestone Texas Proving Grounds located near Fort Stockton, Texas, in the Chihuahuan Desert about halfway between El Paso and San Antonio, Texas. The track was but a small part of the Texas Proving Grounds which occupied 6000 acres of desert.
Certainly the oval track provided a fine venue for breaking the world record, but the perimeter was not fenced and its location in the desolate desert gave the drivers a few extra challenges to think about while traveling 180 plus miles per hour. The lack of any ambient light at night limited sight distances, which compounded the danger of animals straying onto the track. At the planned speeds, by the time a driver saw an animal on the track, it would be too late to take evasive action. The team added lights at the beginning and the end of each 1.5-mile turn to give the drivers some visual help in being aware of the entrances and exits of the turns—but the straights were completely dark. The forward-thinking Tommy Morrison hired guards and placed them at intervals around the track at night to randomly fire shotguns in the air to hopefully dissuade any curious animals from heading toward the track.
The Record Run
The ZR-1 record breaking car was a production-based test car with a few changes for added safety. The LT-5 engine came directly from Mercury Marine and was strictly stock except for headers, open exhaust and recalibrated engine controls to accept racing gas. Changes to the interior included a roll cage and safety equipment, and a telemetry system took the place of the passenger seat. The chassis had a 48-gallon fuel cell, transmission and rear axle coolers, unique 17-inch radial racing tires, and the rear anti-roll bar was removed to accommodate the fuel cell.
Outside, the side mirrors were removed; the front end lowered; an enlarged, reinforced front air dam with ultrasonic “anti-animal” whistles was added; racing lights were installed in the normal fog light and turn signal light mounts; and a pair of aircraft landing lights were installed in the front license plate space. Every preparation the Team could think of was in place—was the ZR-1 ready for the world stage?
On Thursday morning, March 1, 1990 it was time for John Heinricy to strap himself into the ZR-1, crank it up and get things under way. John went out for a recon lap and as he came around he crossed the starting line at about 9:55 a.m., the game was afoot! The weather was about 35 degrees Fahrenheit, windy, and overcast. As the day wore on, the weather didn’t improve and throughout the night, in addition to the hazards of driving in the darkness, the drivers had to face wind gusts, intermittent drizzle and snow, and patches of fog. Fortunately, the ZR-1 just ran and ran with only a couple of very minor mechanical issues that were easily corrected.
The first world speed record to fall was for 5,000 km at 3:36:06 a.m. Friday morning. The 24-hour record was next to go with Tommy Morrison at the wheel at 9:55:12 a.m. on Friday and finally the 5,000 mile record succumbed at 28 hours, 46 minutes and 12.426 seconds after the start.
The Team accomplished what few believed could be done—they set the following world land speed records:
- 5,000 km at an average speed of 175.710 mph
- 24 hours at an average speed of 175.885 mph
- 5,000 miles at an average speed of 173.791 mph
Tommy Morrison summed up the Team’s feelings best when he said, “It was very difficult to achieve, but I’ve owned Corvettes since 1962 and there’s nothing I wanted to do more than break this record.”
ZR-1: The Production Car that Set an Unlimited Land Speed Record
Bear in mind that the record broken by the ZR-1 is for unlimited vehicles and is not restricted to stock vehicles. Indeed, the Mormon Meteor III that set the record in 1940 was a purpose-built land-speed racer powered by a 25.7 liter aircraft engine.
The fact that the record was broken by a production-based ZR-1 cemented Corvettes reputation as a World Class sports car and is a massive tribute to the tenacity and skills of all those who planned the challenge and drove the car—and a big raspberry for those who said it couldn’t be done.
The record-breaking ZR-1 currently resides in the National Corvette Museum, a fitting place to honor its accomplishments. Team members John Heinricy, Jim Minneker, and Tommy Morrison remained very active in the Corvette community and were subsequently inducted into the Corvette Hall of Fame. The Mormon Meteor III lived a difficult life after retiring from competition and fell into disrepair. Fortunately for all race fans, it was rescued and restored by Ab Jenkins’ son Marvin and can be seen at the Price Museum of Speed in Salt Lake City, Utah.
Corvette from the Inside, by Dave McLellan, © 2002 Dave McLellan and Robert Bentley Inc.
The Corvette Story http://corvettestory.com/Corvette-zr-1.php
National Corvette Museum https://www.corvettemuseum.org/
The Old Machine Press https://oldmachinepress.com/2014/06/11/jenkins-mormon-meteor-iii/
Price Museum of Speed http://pricemuseumofspeed.org/
Book Review – “Heart of the Beast” https://books.google.com/books?id=_OfLH86BVPAC&pg=PA111&lpg=PA111&dq=7.7+mile+test+track+near+ft.+stockton+tx&source=bl&ots=fRhFmCosBB&sig=ACfU3U28UUIXGegg0MGb7mTulN8JtjDb3g&hl=en&sa=X&ved=2ahUKEwi7zJzb-qrkAhVtvlkKHaovBacQ6AEwA3oECAkQAQ#v=onepage&q=7.7%20mile%20test%20track%20near%20ft.%20stockton%20tx&f=false